A CLOSED CIRCUIT, FREE FLOW, underwater breathing system is presented through this invention. The approach employs helmeted divers operating from an underwater enclosure. The enclosure is equipped with the usual breathing gas reconditioning devices, with emergency gas supplies, etc. and additionally is provided with or connected with a gas pumping module.
The aims of the invention are: To free the diver of encumbrances, to conserve and recirculate breathing gas normally lost by divers, to remove harmful carbon dioxide, to reduce loss of body temperature, to prevent lung congestion, and to provide a means of eliminating lung fatigue.
Substantial economies are possible and these become very significant as diving progresses to deeper depths. The consumption of helium gas, a limited resource, is reduced to a bare minimum. Heating the diver and his inspired gas increases his usefulness and prevents lung damage. Lung fatigue, inherent in demand systems and most apparent at deep depths, is virtually eliminated. Communications are optimized and removal of carbon dioxide is assured.
This invention, in general, relates to an underwater breathing system and, in particular, to an underwater breathing system characterized by a closed circuit, non-demand, or free-flow circulation pattern wherein a diver is supplied via an umbilical from a source not carried by the diver.
A common type of underwater breathing apparatus, called an OPEN CIRCUIT rig, is one wherein a diver is supplied via an umbilical from a source located on the surface or from a diving chamber, habitat, or similar underwater device The breathing mixture is supplied to the diver's helmet or face mask at a pressure in excess of the depth at which he intends to go, and the flow is throttled in accordance with his needs. His exhaled breath, which contains an amount of reusable oxygen, valuable helium, undesirable carbon dioxide, and other gases, is lost to the surrounding water.
Devices utilizing helmets or face masks have been developed which are carried by the diver to permit his exhaled breath to be purified by recirculating it through a carbon dioxide absorber, the impetus being provided by allowing the breathing gas supply from an umbilical to enter a venturi located within the absorber. This method is known as SEMI-CLOSED CIRCUIT CONSTANT VOLUME and is not as wasteful as OPEN CIRCUIT; but while less gas is consumed, all gas supplied is eventually lost. In addition, the diver is encumbered by the device he wears and the performance of the venturi degrades rapidly with increases in depth, allowing a build-up of carbon dioxide.
Not being demand devices, there is no resistance to breathing using OPEN CIRCUIT or SEMI-CLOSED CIRCUIT methods.
If a diver were to use a CLOSED CIRCUIT SELF-CONTAINED BREATHING APPARATUS wherein all of the diver's exhalation is recirculated through a carbon dioxide absorber, oxygen replenished, as required, and helium added to compensate for losses, a much more efficient utilization of the gases is effected. However, the diver is very encumbered and his bottom time limited by his gas supply and the life of his CO.sub.2 absorber. These devices are electromechanically complex, have poor communications due to the necessary oral nasal mask, and the inherent breathing resistance of demand apparatuses.
A SEMI-CLOSED CIRCUIT CONSTANT MASS FLOW RATE breathing device which is similar to the constant volume device, uses an umbilical, and since it is worn, it too encumbers the diver. While potentially having a longer capability, it is limited by the life of the CO.sub.2 absorber. This device suffers from mechanical complexity. It has poor communications because of the oral nasal mask, unavoidable breathing resistance, and is position sensitive due to its breathing bags.
The advances in diving technology have ushered in saturation diving techniques and underwater habitats where men can work and live for extended times in a water environment. The atmosphere within these enclosures may be self-contained or replenishable from the surface but is always maintained at proper breathing conditions purified of carbon dioxide, etc., and reconstituted with oxygen as required.
Attempts have been made to supply this breathable environment to divers through the use of a pump and to prevent its loss by providing means for the exhaled gas to return to the enclosure for repurification. These devices generally employ conventional breathing bags, mask, etc. and are of the demand type, supplying breathing gas only upon inhalation of the diver.
The unavoidable breathing resistance of all demand types of breathing devices causes the diver to think he is not getting an adequate amount of gas and continuous deep overbreathing usually occurs. This results in fatigue of the diaphragm and chest muscles, leading to involuntary reduced breathing. In addition, the cold gas causes mucus to be secreted within the lungs which leads to congestion, and contributes to a significant reduction in the diver's body temperature. The above is especially critical at deep depths.
It is, therefore, a primary objective of the present invention to provide a CLOSED CIRCUIT, FREE-FLOW breathing system that a diver may be supplied with a breathable gas mixture from a source not carried by a diver.
Another object is to provide a CLOSED CIRCUIT, FREE-FLOW breathing system wherein the diver is supplied from an atmosphere within an underwater enclosure and in which the diver may descend to a depth below or ascend to heights above the enclosure.
Another object is to provide a CLOSED CIRCUIT, FREE-FLOW breathing system of the type described wherein a diver is not subjected to dangerous eye, face, or thoracic squeeze.
Another object is to provide a CLOSED CIRCUIT, FREE-FLOW breathing system wherein breathable mixture is supplied by a compressor pump and removed by a depressor pump, these pumps to be driven by a suitable variable or constant speed prime mover.
Another object is to provide a CLOSED CIRCUIT, FREE-FLOW breathing system wherein the diver's breathing gas is heated to a suitable temperature to prevent harmful physiological effects that would reduce his capabilities.
Another object is to provide a CLOSED CIRCUIT, NON-DEMAND breathing system that can be used below the surface, supplying submerged divers indirectly via a suitable underwater enclosure. The purification and reconstituting of the breathing gas may be done with suitable equipment attached to the underwater enclosure from which divers operate.
In accomplishing at least certain of the foregoing objectives, a method and apparatus are presented wherein underwater enclosure means operable, to permit diver ingress and egress, is provided. A helmet means is provided which is operable to provide a breathable atmosphere for a diver at a submerged location. An umbilical means extends between said underwater enclosure means and this helmet means. A flow of breathable gas is continuously circulated from the underwater enclosure means through supply conduit means of the umbilical means to the interior of said helmet means and from the interior of said helmet means back through return conduit means of the umbilical means to said enclosure means. The continuous flow of gas returning from the helmet means through said return conduit means is caused to be transmitted to return tank means located remote from a diver wearing the helmet means.
Gas is removed from the return tank means by operation of depressor means. The depressor means is operable to maintain a relatively low pressure in the return tank means, which lower pressure tends to promote a continuous flow of gas from the helmet means through the return conduit means to the return tank means.
Gas is transmitted from the depressor means to compressor means at a location remote from the diver.
Gas is transmitted from the compressor means to supply tank means, with the compressor means being operable to pressurize gas in said supply tank means to a relatively higher level.
Gas is transmitted from the supply tank means through the supply conduit means continuously to the interior of said helmet means, with the relatively higher pressure in said supply tank means being operable to induce and sustain a continuous flow of gas from the supply tank means through the supply conduit means to the interior of the helmet means. The rate of continuous flow of gas (from the supply conduit means through the interior of the helmet means and into the return conduit means for return to the enclosure means) is regulated.
A supply of breathable gas, operable to be transmitted to the helmet means through the supply conduit means independent of gas flowing from said supply tank means, is provided at a surface location. At a location remote from the diver, gas reconditioning means is provided which is operable to receive gas from at least one of said compressor or depressor means, remove carbon dioxide at least in part therefrom, and transmit gas with carbon dioxide removed at least in part therefrom to the supply tank means.
The continuous flow of gas from the supply conduit means into the interior of the helmet means and back into the return conduit means is operable to provide a continuous flow of breathable gas passing across the face of a diver positioned within said helmet means and generally displace from the vicinity of said diver face gas exhaled by said diver and induce this displaced, exhaled gas to flow out of said helmet means back into the return conduit means for return to said enclosure means.